Dreams could one day be recorded electronically, allowing them to be interpreted, scientists say. Experiments in which volunteers had electrodes surgically implanted deep inside their brains had already allowed researchers to ‘read’ people’s minds, said Dr Moran Cerf. The breakthrough could eventually lead to the development of a dream recorder, he added. ‘We would like to read people’s dreams,’ Dr Cerf said. ‘It would be wonderful to read people’s minds when they cannot communicate, such as people in comas.’

In tests on 12 epilepsy patients, electrodes recorded the activity of neurones in a part of the brain called the medial temporal lobe, which plays a major role in human memory and retention. The volunteers were shown more than 100 familiar images, such as Marilyn Monroe and Michael Jackson, on a screen. From these, pictures that had triggered responsive neurons in different parts of the subjects’ MTLs were selected.

The patients were then shown two of these images superimposed and told to think about one of them, while the scientists ran the neuron patterns through a decoder. When the decoded information was fed back on to the superimposed images, the one whose neuron was firing more quickly was enhanced, while the other faded.

By watching this online feedback, more than two-thirds of subjects were able to make their targeted image completely visible and entirely eliminate the other picture. By observing which brain cells lit up and when, Dr Cerf and his US colleagues, Christof Koch and Itzhak Fried, said they were in effect able ‘read the subjects’ minds’. The study is published in the journal Nature.